Hey guys, I need your help again. I need to check to see what pushrod length I need to order. I did a search and was confused with the varying methods so I thought I would ask in this post. A few particulars on the valvetrain:

Comp Cams 248/254 duration with .648/.648 lift hydraulic roller (taller lifters). 114 LSA on a 110 base circle. I am running Comp Cams Pro Magnum roller rockers. The Pro Topline heads manufacturer suggest an 8.5 and 9.5 length pushrods.

Can anyone give me a step-by-step process that I can follow. I am picking up the pushrod length checkers tomorrow.

Thanks in advance!

http://www.compcams.com/catalog/278.html
http://www.compcams.com/catalog/279.html

The problem with the Comp Cams instructions is that you can't see the contact point on the valve tip very well, and not at all with non-roller rocker arms.

This is easily "cheated" by cleaning off the oil from the tip and pushrod end, and wiping a black magic marker (I've been known to use machinist's blue as an alternate.) across the valve tip. Put it together, including proper valve lash or preload, roll the engine over a couple of times, check where the black dye has been worn off.

Don't forget, if you have hydraulic lifters, you MUST use checking springs instead of valve springs. Without the super-light springs, your readings will be skewed by the collapse of the lifter plunger.

You can also use a solid lifter as your checking piece, with your light springs, to keep from getting the hydraulic plunger error.

Mark the tip of the valve with wjite lithium or gear marking compound; that way you can easily see the pattern when you take the rocker back off after turning the engine through a few cycles.

OBTW - if you're dummying the crank into the block without pistons in order to measure something else, and it happens to be convenient to stick a head on and do this with no pistons in the block, it's a whole lot easier at that stage.

Originally posted by Chas67:
Hey guys, I need your help again. I need to check to see what pushrod length I need to order. I did a search and was confused with the varying methods so I thought I would ask in this post. A few particulars on the valvetrain:

Comp Cams 248/254 duration with .648/.648 lift hydraulic roller (taller lifters). 114 LSA on a 110 base circle. I am running Comp Cams Pro Magnum roller rockers. The Pro Topline heads manufacturer suggest an 8.5 and 9.5 length pushrods.

Can anyone give me a step-by-step process that I can follow. I am picking up the pushrod length checkers tomorrow.

Thanks in advance! Did you buy a pair of the adjustable check puch rods yet?

Quick, easy, inexpensive & IMO just as accurate as the other methods--Pushrod length checker Jeg's part # 778-66789 3/8" SB, # 778-66790 7/16"
SB, #660-42133 BB. Costs $12.99 to $16.99. Just be absolutely sure that you're on the base circle of the cam & it'll be right. You don't have to change springs either. :D

BL

I got the Comp Cams pushrod length checkers yesterday and will be measuring tonight. I will keep you posted.